Patent GB-717320-A (GB)
Title: Automatic dust handling plant
Inventor: MORGAN JAMES
IPC: F23J3/06
Filed: 1951-05-29
Abstract: 717,320. Pneumatic conveyers. B.V.C. INDUSTRIAL CONSTRUCTIONS, Ltd. July 1, 1952, [May 29, 1951.] No. 12585/51. Class 78 (1). In means for pneumatically removing ash, dust or other finely divided matter from any one of a series of collecting hoppers forming components of industrial plant, a central electrical control panel provided with a starting switch controls the operation of a secondary local switch panel which in turn controls the operation of dust removal from one hopper, which operation when completed causes the energization of a further secondary local panel and actuates means for indicating to an attendant whether the operation has been carried out successfully or otherwise. The throat i of each hopper 2 is connected to a pipe line 25 by an elbow 4, Fig. 2, containing a valve 5, which normally is actuated by a three phase reversible electric motor 7, but in an emergency can be operated by the hand wheel 6. Limit switches 8, 9 in the circuit of the motor 7 are opened by the valve 5 when the latter is fully opened or closed. The pipe line 25 leads to cyclone separators 26, valves 27 being provided to isolate any separator not in use. Each cyclone discharges into a primary container 30, the outlet from which is controlled by a wide-opening gate 31, Fig. 5, actuated by a hydraulic ram and cylinder 32. Dust passes through the gate to a similar secondary container 33 and thence to a storage bunker 36. A valve 37 controls the discharge from the bunker to a conveyer 38. The section 39 between the containers 30, 33 has an air inlet 40 on one side and a valve 41a on the other which is connected by a pipe 41 to a branch 42 of the line 29 leading to the pump 28. Air inlets 10, Fig. 2, enter the sides of each elbow 4 and are connected by pipes 12 provided with check valves i 1 to a common air chamber 13 to which air is admitted through an orifice plate 14. The chamber is connected by a pipe 15 to high and low fluid pressure electric switches 16, 17 mounted on a local instrument panel 18 which contains the electrical equipment required for the interpretation, of the various conditions which may occur in the hopper. Air passing through the plate 14 is drawn through the cyclone by the pump 28. A dust level indicator 19, 20 mounted on each hopper comprises a pivoted paddle 20 which normally is vertical. When electrical impulses are applied to an indicator, the paddle will either rock or remain stationary depending on the absence or presence of surrounding dust and cause the opening or closing of remote relay switches. The indicators are connected electrically to the panel 18 and main panel. The main panel is situated at an observation point and provides information for all the hoppers in any automatic series. Air jets 21 are inserted in the tapering lower section of the hopper where bridging is likely to occur. These jets are supplied with air from a source 24 through a pipe 22, the flow being controlled by a magnetically-actuated valve 23 which is energized when bridging, &c., occurs in the hopper. Each panel 18 has a relay responding to the closing of a main switch on the main panel and giving a sustained circuit to a series of switching devices operated by cams on a rotary shaft 69 to provide sequence switching for the continuous operation of emptying the hoppers in succession with means for automatically repeating the process if a signal is received that the dust has not been removed entirely, to close the hopper isolation valve and open valves to compressed air jets to clear any obstruction in the hopper being emptied and later to close the isolation valve and restart dust evacuation. Means are provided if the operation is successful to energize automatically the initial relay of the panel of the next hopper and means are also provided which come into operation after a series of unsuccessful attempts to empty any hopper and give an alarm signal on the local and central panels, open all circuits connected with that hopper and start the discharging mechanism for the next hopper in the series.